UBC Theses and Dissertations
Characterization of yttria stabilized zirconia and carbon nanotube doped : YSZ ceramic composites fabricated by spark plasma sintering Karanam, Abhinav
Zirconium oxide doped with Yttria has been recognized as a candidate material for thermal barrier coatings (TBC) due to its high thermal stability, inertness and corrosion resistance. Literature suggests that addition of Carbon Nanotubes (CNTs) to technical ceramics (e.g., Alumina) may significantly enhance the mechanical properties of the ceramic composite. However, the agglomeration of CNTs in the ceramic matrix during the fabrication process generally has a detrimental effect on the ceramic composite’s mechanical properties. It was seen that during conventional sintering processes, CNTs may disintegrate when exposed to sintering temperatures for a long time, thus creating a need to identify a novel technique for successfully fabricating CNT-ceramic composites. Spark Plasma Sintering (SPS) is a novel method for fabricating ceramic composites, which are difficult to fabricate using traditional methods. In this work, 8mol% YSZ was fabricated via SPS process, and the effect of varying sintering parameters was investigated. Also, the effect of adding Single-Wall CNTs (SWCNTs) and Multi-Wall CNTs (MWCNTs) on the densification behavior, mechanical and thermal properties of the CNT-YSZ composites were studied. The results suggest that MWCNTs did not have a very pronounced effect on the densification of YSZ and no appreciable improvement in the hardness was observed. This was likely the result of MWCNT agglomeration in the ceramic matrix. In contrast, the SWCNTs had a significant effect on the hardness of the ceramic composite with ~ 71% increase in hardness from 0 to 1wt% SWCNT addition. However, SWCNTs were also seen to hinder densification. The thermal conductivity of the SWCNT – YSZ ceramic composites was seen to be a function of the concentration of the SWCNTs in the composite.
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